Since the introduction of electrical power distribution systems in the late 19th century, there has been a need to monitor their operational and electrical characteristics. The ability to collect, analyze, and respond to information about an electrical power system can improve safety, minimize equipment loss, and ultimately save time and money. To that end, monitoring devices were developed to measure and report such information. These monitoring devices may have a separate user interface for reporting such information from the monitoring device itself. The user interface typically includes a display that is remote from the main monitoring device. The remote display beneficially allows the monitoring device with the actual electrical connections to be safely moved a distance away from the user and provides installation flexibility by mounting elsewhere the main monitoring unit, which is physically larger than the remote user interface.
Traditional remote displays have been driven by RS-232 or RS-485 transceivers. RS-232-type transceivers have a single-point interface and are not multi-master. RS-232 transceivers limit connection from one meter to one display. Therefore, if a user wishes to monitor readings from multiple metering devices, it is necessary to purchase and install multiple display units. An RS-485 transceiver is multi-drop, but typically has a single master. A problem that arises in a specific application of multi-tenant monitoring environment (energy monitoring in apartments or high-rise condominiums) is the inability to use a single display to monitor multiple circuits in a cost-effective way.
Furthermore, in tenant monitoring, normally the display must be isolated from the electrical circuit via galvanic or optical isolation. For RS-485 transceivers, this means that three wires must be isolated. Additionally, traditional remote displays driven by RS-232 or RS-485 can transmit data only at speeds up to 100 kbit/s.
Furthermore, these traditional monitoring systems are limited in their flexibility because of the one meter to one display or single master limitation. A user cannot simply install only those devices which he wishes to utilize because of these limitations.
There is thus a need for a lower cost for remote displays. There is also a need for improved scalability options for remote displays. There is also a need for single display able to read on multiple metering devices. There is also a need for multiple displays to read on a single metering device. Finally, there is a need for multiple displays to display data from multiple metering devices. Aspect of the present invention addresses these and other needs.